We are working on a quantitiative end-group determination to be used in our measurements of breakdown rates of specific brain proteins and the bond specificity of brain proteases. The purification of peptidases continues: we are utilizing inhibitors to separate the various enzymes, to study the splitting of proline peptides, especially, and TRH. We started to study the production of peptide intermediates. Concomitantly with these studies we are measuring the uptake of peptides by the brain. Developmental changes in protein turnover are being investigated by measuring specific protein components, and we are measuring the metabolism of membrane proteins under various conditions.